A total of 660 students sat for the Chinese mock exam. ¹₂ of the boys and ⁸₉ of the girls passed the mock exam. The same number of girls and boys failed the mock exam. How many more girls than boys passed the mock exam?
Fraction of the boys that failed the mock exam
= 1 - ¹₂
= ¹₂

Fraction of the girls that failed the mock exam
= 1 - ⁸₉
= ¹₉

Number of boys and girls that failed the mock exam is the same. Make the numerators the same.
¹₂ Boys = ¹₉ Girls

Total number of boys = 2 u
Total number of girls = 9 u

Total number of students
= 2 u + 9 u
= 11 u

11 u = 660

1 u = 660 ÷ 11 = 60

Number of boys that passed the mock exam = 1 u
Number of girls that passed the mock exam = 8 u

Number of more girls than boys who passed the mock exam
= 8 u - 1 u
= 7 u
= 7 x 60
= 420

Answer(s): 420